textproduct: Rapid City

KEY MESSAGES

- Areas of light precipitation continue into Thursday morning.

- Stronger winter storm moves in Thursday evening through much of Friday.

- Mild and drier conditions settle in the remainder of the weekend into early next week.

UPDATE

Issued at 1043 PM MDT Wed Apr 1 2026

Main forecast changes this evening: increasing signals across most guidance supporting fog and low clouds developing overnight into Thursday morning across most of our northern and eastern Plains into the Black Hills on easterly flow, so expanded coverage of both patchy and areas of fog. Radar trends and the fresh suite of HREF CAMs offer consensus in lingering light snowfall across our WINTER WEATHER ADVISORY area in Perkins and Ziebach counties already diminishing and coming to an end over the next several hours, so pulled back the expiration time of the advisory to 6 AM instead of noon tomorrow. Finally, our latest forecast update for the impending winter storm Thursday evening through Friday night came in just a touch warmer with slightly lower QPF south of I-90. Can't say for sure yet if this is a trend, but it did allow rain to mix with the snow longer into Friday and further north compared to earlier projections, redistributed potential light freezing rain coverage (still generally a light glaze possible), and cut down just a touch on storm total snow accumulations from Butte, Mead, and Haakon counties southward (due to longer mixing with rain vs. all snow). Will continue to watch all of this for further changes or trends as the event approaches, but for now we have no confidence to make any changes to the ongoing WINTER STORM WATCH. Stay tuned.

DISCUSSION

(This Evening Through Wednesday) Issued at 211 PM MDT Wed Apr 1 2026

Current upper air models and Water Vapor imagery show southwest flow over the forecast area, as current wave impacting the region sits over WY and CO. 20Z surface analysis shows low centered over WY with a warm front stretching into western NE, a secondary front runs from northwest SD into central ND. Radar currently shows widespread returns over western SD. Winds are generally out of the south to southwest and breezy, with temperatures sitting in the 30s to mid 40s.

As the first disturbance treks across the northern/central plains today and tonight, expect areas of precipitation to continue. Most areas will be rain through this evening (with northwest SD seeing some snow), but will transition to snow as temperatures drop below freezing tonight. Light accumulations under an inch are generally expected, with some areas in northwest SD seeing accumulations of an inch or two through Thursday morning. Precipitation will taper off from west to east as the low exits the region.

After a dry period during the day Thursday, attention turns to the second more strong disturbance affecting the region. Upper closed low traverses over the Rockies, entering the northern plains Thursday night into Friday morning. Precipitation returns out ahead of the low Thursday evening, becoming more widespread in the overnight hours. Temperatures will make this a tricky event, as Thursday afternoon temps climb back into the 40s over northwestern SD to near 60 in southwestern SD. So precipitation will start out as rain, transitioning to snow eventually but timing will be key. Regardless of precip type, widespread wetting rains are expected Thursday night through Friday night with this system. NBM's probability of QPF >= 0.1" sits in the 70-99 percent range over the entire forecast area, while the highest chances for QPF >= 0.5" sit in the 60-90 percent range closer to central SD. Right now the best chances for accumulating snow are in the Black Hills and areas north of I-90. The highest amounts are expected in northwestern SD as well as the higher elevation Black Hills, where the cooler temperatures will be in place. NBM probabilities for 6" or more for these areas sit in the 70-95 percent range. Forecast confidence in exact snow totals remains low as model guidance still shows a wide spread in snowfall totals, given the forecast temperatures during this event.

Precipitation will taper off Friday night into Saturday morning, and dry conditions return for the remainder of the weekend as upper ridge returns over the western CONUS. Highs rebound back into the 40s and 50s for Saturday, and 50s to mid 60s for Sunday. Mostly dry conditions continue through middle of next week, however long range models point to some weak disturbances latter half of next week that may bring chances for light precipitation.

AVIATION

(For the 06Z TAFS Through 06Z Thursday Night) Issued At 955 PM MDT Wed Apr 1 2026

MVFR/IFR conditions will linger across the western/central SD plains overnight. With easterly surface winds overnight, IFR CIGS/VSBY (especially due to fog) will slide westward toward the Black Hills in the next few hours. Some improvement to VFR is expected during the day on Thursday, except across NW SD where MVFR/IFR CIGS should persist through the day tomorrow. Conditions will deteriorate again Thursday night as a strong storm system approaches the region. This will bring widespread rain/changing to snow Thursday night, especially north of the I-90 corridor in South Dakota.

UNR WATCHES/WARNINGS/ADVISORIES

SD...Winter Storm Watch from late Thursday night through late Friday night for SDZ001-002-012>014-024-025-078. Winter Weather Advisory until 6 AM MDT Thursday for SDZ002-014- 078. WY...Winter Storm Watch from late Thursday night through late Friday night for WYZ056-057-060.